Electrical Impedance Sensing Biopsy Sampling Device And Method

Abstract

A biopsy sampling device has an inner trocar having a sharpened tip and a sampling opening. The trocar is slideably engaged in a central cavity of an outer needle with its sharpened tip and sampling opening protruding from an end of the outer needle. Impedance measuring apparatus measures impedance between the inner trocar and the outer needle. In an embodiment, impedance is measured at multiple frequencies and spectral characteristics are determined therefrom. The inner trocar has an insulating coating over those portions of the inner trocar that are located within the central cavity of the outer needle. In an embodiment, the sampling device is used to obtain samples from an organ at points in the organ where impedance differs from an impedance of organ stroma.

1 . A biopsy sampling device comprising:
 an inner trocar having a sharpened tip and a sampling opening;   an outer needle having a central cavity;   an impedance measuring apparatus coupled to measure an impedance between the inner trocar and the outer needle;   the inner trocar slideably engaged within the central cavity of the outer needle such that its sharpened tip and sampling opening protrude from an end of the outer needle;   wherein the inner trocar has an insulating coating over those portions of the inner trocar that are located within the central cavity of the outer needle;   and wherein the inner trocar is adapted to be removed from the outer needle, thereby capturing a sample in the sampling opening.   
     
     
         2 . The biopsy sampling device of  claim 1  wherein the outer needle is insulated except for an uninsulated portion near the end from which the inner trocar protrudes. 
     
     
         3 . The biopsy sampling device of  claim 2  wherein the uninsulated portion near the end of the outer needle has a length of two millimeters. 
     
     
         4 . The biopsy sampling device of  claim 1  wherein the inner trocar is made of ferrous metal. 
     
     
         5 . The biopsy sampling device of  claim 1  further comprising impedance measurement apparatus for measuring an alternating current impedance at at least one frequency between one hundred and one million hertz, the impedance measurement apparatus coupled to at least one of the needle and trocar. 
     
     
         6 . The biopsy sampling device of  claim 5  further comprising an external electrode. 
     
     
         7 . The biopsy sampling device of  claim 1  wherein the impedance measurement apparatus measures alternating current impedance at several frequencies between one hundred and one hundred thousand hertz, and computes spectral parameters from the measurements, and displays at least one spectral parameter to a user. 
     
     
         8 . A method of obtaining biopsy samples from a subject comprising:
 advancing a sampling device into an organ while monitoring impedance characteristics between a center trocar of the sampling device and an electrode selected from the group consisting of an outer needle of the sampling device and an external electrode;   displaying to an operator at least one impedance characteristic, the impedance characteristic updated regularly;   upon observing a change of impedance, withdrawing the center trocar of the sampling device to obtain a biopsy sample of an inclusion in the organ.   
     
     
         9 . The method of  claim 8  wherein the electrode selected from the group consisting of an outer needle of the sampling device and an external electrode is an outer needle of the sampling device. 
     
     
         10 . The method of  claim 8  wherein the at least one impedance characteristic displayed to an operator includes at least one spectral parameter. 
     
     
         11 . The method of  claim 10  further comprising advancing the sampling device past a point where the change of impedance was observed such that a sampling opening of the center trocar is positioned within the inclusion in the organ. 
     
     
         12 . A method of diagnosing inclusions within an organ within a subject comprising:
 advancing a sampling device into the organ while monitoring impedance characteristics between a center trocar of the sampling device and an outer needle of the sampling device;   displaying to an operator the impedance characteristics;   upon observing a change of impedance in the displayed impedance, positioning the sampling device such that a sampling opening of the sampling device is positioned to capture a biopsy sample of the inclusion;   removing the biopsy sample from the organ; and   performing pathological examination of the biopsy sample.   
     
     
         13 . The method of  claim 12  wherein the at least one impedance characteristic displayed to an operator includes at least one spectral parameter. 
     
     
         14 . The method of  claim 13  further comprising:
 obtaining impedance measurements and biopsy samples from a plurality of locations within the organ; and 
 using both the impedance measurements and pathological examination of the biopsy samples to determine the diagnosis. 
 
     
     
         15 . A biopsy sampling device comprising:
 a first conductive part having a sampling opening;   a second conductive part adapted to cover the sampling opening;   an impedance measuring apparatus coupled to measure an impedance between the first part and the second part;   wherein a part selected from the first part and the second part has an insulating coating over those portions of the part that may contact another part during insertion of the sampling device into an organ.